Karyotypic analysis of Silybum marianum using multivariate statistical methods

In this research work, Intra-species karyotypic diversity for 17 populations of Silybum marianum from different geographical regions of Iran along with one population from Hungary were investigated. To prepare the appropriate chromosomal specimen, one and a half centimeters of root tip were isolated, after using fixation of pre-treatment, the picture were taken from the karyotypes which prepared and the chromosome base number of all of them was  x = 17, therefore the number of chromosomes obtained 2n = 34. In terms of karyotypic symmetry indices DRL, S%, TF%, A1 and A2, there were significant differences between ecotypes at probability level of 1%, which indicates that there were genetic diversity between the studied ecotypes. Regarding these results, the Ramhormoz ecotype and then the Shushtar ecotype were considered as the most asymmetric and most advanced ecotypes and the ecotype of Najaf-Abad and ecotype of Karaj-2 were considered as the most symmetrical and incomplete ecotypes. Based on the cluster analysis, the karyotypic characters of the populations were divided into three groups. The greatest difference was observed between the two Ramhormoz and Najafabad ecotypes. To determine the contribution of each karyotypic trait in the creation of diversity among ecotypes, factor analysis was carried out and the first, second and third factors accounted for more than 87% of the variation among the populations. The results of karyotypic analysis showed that there is a high karyotypic variation among Silybum marianum ecotypes in Iran, so that they can be used in breeding programs and widening genetic diversity in gene pools.